Bernard Tomic ought to be the most popular athlete in Australia right now.

Yet some time tomorrow, probably no earlier than 10am GMT (in a primetime evening slot ordained by national television), the 18-year-old son of Bosnian and Croatian parents who emigrated to Australia from Germany when he was three will stand across the net from the peerless Rafael Nadal in an arena named in honour of the nation's greatest player, Rod Laver, and wonder.

He will wonder if this stage, the third round of the Australian Open, is too big for him. He will wonder if he really is the 199th best player in the world and if he deserves to be regarded as any better than that just now. He will wonder if Nadal has even a strain of mercy in his Spanish blood – and the answer to that question, in the negative, will galvanise him more than anything else as he seeks to avoid embarrassment on a grand scale.

Tomic, a player of deceptively languid skills, a prodigy who has been indulged and derided in equal measure in a short and blazing career, must fight for his dignity. If Nadal humiliates him – and the consensus is Tomic will do well to win a handful of games – his best response will be to take it in good heart, give a short, respectful response, and move on. There will be other days.

Yet he may be seduced by history. Who here could forget the deeds of Mark Philippoussis in 1996, when he destroyed Pete Sampras on the same court at the same stage of the same tournament?

While Scud was a year older, at 19, and ranked 40th in the world, it was a spectacular achievement by an Australian teenager on home soil. Back then, the buzz for Philippoussis energised the entire country; even though there is an obvious sense of anticipation about this match, it is not all about Tomic, oddly. And, more than all of the other doubts that flood his mind, Tomic will wonder how much his compatriots really want him to win.

Tomic should be lauded from Darwin to Melbourne. He ought to be riding a wave of sentiment that could add a game or two to his score. Australians are famous for their loyalty to their sporting heroes, after all – but they are also unforgiving for transgressions that have precious little to do with an athlete's calling.

When Michael Clarke walked out to bat at the Sydney Cricket Ground, his home ground, as captain of the Australia team against England this month, the booing that greeted him, shamefully, included local content. Clarke, like Tomic, suffers from the perception that he is too pleased with himself, too ready to accept the gifts of fame without returning to the favour to those who made him famous.

When a 17-year-old schoolboy crashed a cricket press conference this week to lecture Clarke on the shortcomings of his batting, there was little sympathy for the player. He had committed the cardinal sin of being young, rich, talented and not quite humble enough. It is wrong, and unfair. That said, had Clarke come through the Ashes series with anything like a respectable average with the bat, he might have been forgiven.

Tomic, similarly, is seen as overrated and under-performing, a cosseted and sulking prince. He rejected an offer to practise with Australia's No1 player Lleyton Hewitt in 2009, issuing the killer missive through his agent: "Lleyton's not good enough."

That spat was sorted, eventually. The kid, after all, was 16. He is all of 18 now, though; and he carries himself with a little more style, without shedding the arrogance that putative champions deem obligatory.

On the eve of this match, for instance, Tomic predicted his soft-ball tennis, which so comprehensively bamboozled Nadal's Spanish compatriot Feliciano López in three sets in the second round, would give the best player in the world much pause for thought. He could be right. But that pause is likely to be tellingly short, and retribution fierce.

Nadal can do no wrong. He brings nine grand slam titles to the court and an aura as vivaciously imposing as anyone since Jimmy Connors. Alongside Roger Federer, his only peer, Nadal rules the heart of the tennis fraternity. He is humble, accessible and almost universally loved.

The young Australian, however, has no such slavering constituency. As much as the media would want him to pull off the greatest upset of modern times in a grand slam, those who pay to watch him are not convinced he is the sort of champion they want – not yet anyway. He might grow into a calmer version of the volatile spoilt brat of their perception, but there is much rehab of his reputation left to do.

The first lesson in that process begins today. If Tomic takes from it what he can, it could be the making of him.